Answer to Question #44284 in Mechanics | Relativity for [e-mail]

Question

We all believe that Einstein's theory of relativity is correct and it is proved as well, but how an object shrink to nothing and it's mass becomes infinite if it is moving at speed of light?How an object can have infinite mass and shrink to nothing at same time?

Answer 1

For an observer actually traveling at thespeed of light, the equations of Special Relativity predict that time would come to a complete standstill, and length would shrink to nothing. If an object were ever to reach the speed of light its mass would become infinite. However, to move an infinite mass would take an infinite amount of energy–more energy than there is in the entire universe. Thus nothing can ever attain the speed of light. Nothing, that is, except light. Light travels at the speed of light. And it does so because it is not a material object; its mass is always precisely zero.